The Dart Herald was another commercial failure, nice to fly, but only 40 built. I attended a dining in night at RAF Northwood in 1961 when Sir Frederick Handley Page gave a rather bitter speech. HP had refused to join two new consolidated Aviation Groups, BAC and Hawker Sddely I think and the Herald had been side lined in favour of the HS 748/Andover for the RAF.
Back to the thread. The speed range of the TP in the Gulf area was 45kts to 85kts, 90 if you managed to close the cooling gills a bit.